1. Field of the Invention
The present invention relates to an apparatus for re-slicing a semiconductor wafer, particularly for re-slicing the semiconductor wafer from its periphery edge into two sheets through the center portion of the core thickness of the semiconductor wafer to obtain thinner sheets, and more particularly to an improvement in loading an unprocessed wafer on a re-slicing machine and unloading the processed wafer from the same machine.
2. Description of the Prior Art
Japanese Patent Provisional Publication No.Sho 64-19729 and Japanese Patent Provisional Publication No.Hei 1-293613 disclose the processes of dividing a semiconductor wafer into two sheets, which are made of single crystal silicon, for making substrates for discrete components to be used for transistors, diodes or the like. In order to avoid the waste of costly raw material such as the single crystal silicon, a semiconductor wafer is re-sliced into two further sheets from the center of core thickness so that two sheets of substrates for the discrete components are simultaneously obtained.
U.S. Pat. No. 4,261,781 discloses a process for re-slicing a semiconductor wafer into two sheets. However, this patent is not directed to a process for making a substrate for a discrete component. In general, however, not only this U.S. patent document but also the other patent documents disclosed above, do not set forth an apparatus for a re-slicing process in cooperation with a loading and unloading apparatus.
On the other hand, the Applicant of the present invention has disclosed in Japanese Patent Provisional Publication No.Hei 2-10727, published on Jan. 16, 1990, a process for re-slicing a semiconductor wafer and an apparatus for loading an unprocessed wafer on a re-slicing machine and then unloading the processed wafer from the re-slicing machine.
Generally, a requirement for such an apparatus for re-slicing semiconductor wafers is to provide the following apparatus since conventional wafers are handled one by one. Such apparatus should include:
(a) A loading mechanism to load an unprocessed semiconductor wafer on a re-slicing machine;
(b) A slicing mechanism to re-slice the above unprocessed wafer which has been loaded by the above loading mechanism; and
(c) An unloading mechanism to unload the processed wafer from the re-slicing machine in which it has been re-sliced by the above slicing mechanism.
Conventionally, since it is time-consuming to load and unload the semiconductor wafer as positioned as described in the above paragraphs (a) and (c) (other than paragraph (b)) by using conventional re-slicing systems, it is necessary to improve the total productivity relating to paragraphs (a) and (c). In other words, it is necessary to speed up the loading and unloading steps of the semiconductor wafer onto and from a slicing machine. However, the above apparatus involves disadvantages since the semiconductor wafer is easily breakable due to the thin shape and breakable properties, and may therefore break upon speeding up of the loading of the semiconductor wafer.